Hurricane JOHN

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HURRICANE JOHN DISCUSSION NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP112006
800 AM PDT TUE AUG 29 2006
JOHN HAS CONTINUED TO INTENSIFY THIS MORNING...AND FIRST LIGHT
VISIBLE IMAGERY SHOWS AN IMPRESSIVE BANDING FEATURE AND AN OBSCURED
EYE FEATURE TRYING TO DEVELOP. THESE FEATURES ARE ALSO APPARENT ON
A RECENT TRMM MICROWAVE PASS FROM 1156 UTC. DVORAK CLASSIFICATIONS
FROM TAFB AND SAB WERE 65 KT AND 75 KT RESPECTIVELY...AND THE
INITIAL INTENSITY IS A BLEND OF TWO AND IS SET AT 70 KT. JOHN IS
NOW THE SIXTH HURRICANE OF THE EAST PACIFIC HURRICANE SEASON. JOHN
IS IN A CONDUCIVE ENVIRONMENT OF LOW SHEAR AND VERY WARM WATERS FOR
CONTINUED STRENGTHENING. THE OFFICIAL INTENSITY FORECAST TAKES
JOHN TO A CATEGORY 3 HURRICANE IN 24 TO 36 HOURS...WHICH FOLLOWS
CLOSELY WITH THE SHIPS...GFDL...AND FSU SUPERENSEMBLE INTENSITY
GUIDANCE...AS WELL AS THE PREVIOUS ADVISORY. IN THE LATER
PERIODS...THE GFDL MODEL WEAKENS JOHN SIGNIFICANTLY DUE TO THE
PROXIMITY OF IT'S TRACK FORECAST TO LAND. THE OFFICIAL TRACK
FORECAST MAINTAINS THE HURRICANE OVER WATER THROUGH FIVE DAYS AND
GRADUALLY WEAKENS THE CYCLONE IN DAYS 4 AND 5 AS A RESULT OF COOLER
WATERS.
THE INITIAL MOTION IS 290/8...SLIGHTLY FASTER THAN BEFORE. JOHN IS
EXPECTED TO CONTINUE ON A WEST-NORTHWEST TRACK FOR THE NEXT 3 TO 4
DAYS WITH SOME INCREASE IN FORWARD SPEED. THE HURRICANE IS
FORECAST TO BE STEERED ALONG THE SOUTHWESTERN PERIPHERY OF A MID-
TO UPPER-LEVEL RIDGE BUILDING ACROSS NORTHERN MEXICO. MOST OF THE
MODEL GUIDANCE IS IN CLOSE AGREEMENT WITH THIS SCENARIO...HOWEVER
THE GFDL MODEL ANTICIPATES THE WESTERN EXTENT OF THE RIDGE TO BE
FURTHER TO THE EAST ALLOWING THE HURRICANE TO MOVE CLOSER TO THE
WEST COAST OF MEXICO AND EVENTUALLY OVER THE BAJA PENINSULA. THE
OFFICIAL TRACK FORECAST STAYS CLOSE TO THE MODEL CONSENSUS AS WELL
AS CLOSE TO THE PREVIOUS ADVISORY.
AS A RESULT OF THE CONTINUED STRENGTHENING OF JOHN...THE WIND RADII
HAVE BEEN EXPANDED. THIS HAS PROMPTED THE GOVERNMENT OF MEXICO TO
ADJUST THE WATCHES AND WARNINGS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 29/1500Z 14.3N 99.0W 70 KT
12HR VT 30/0000Z 14.8N 100.4W 85 KT
24HR VT 30/1200Z 15.6N 102.2W 95 KT
36HR VT 31/0000Z 16.7N 104.3W 105 KT
48HR VT 31/1200Z 18.2N 106.2W 105 KT
72HR VT 01/1200Z 20.5N 110.0W 100 KT
96HR VT 02/1200Z 21.0N 112.5W 85 KT
120HR VT 03/1200Z 21.5N 115.5W 65 KT
$$
FORECASTER MAINELLI/PASCH
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